In the art of printing, the printer has always devoted special attention to the manner in which he has handled the freshly printed sheets so that the ink would not smear. The ink on freshly printed sheets never dries immediately, and the ink is particularly prone to smear when the sheets are stacked one upon another.
As printing presses developed and became capable of achieving increasingly higher printing speeds, the probability also increased greatly that the freshly printed sheets would become smeared. Then, with the recognition of this problem, many different methods were devised to lessen the chances of ink smearing as the printed material passed through various components of a printing press, or as the printed sheets were collected in stacks at the end of the printing process.
Rotary printing presses, whether of the offset type, letter-press type, or multicolor type, always include a transfer mechanism to guide the movement of the freshly printed sheets between two stages of the printing operation. The transfer mechanism may be in the form of a transfer drum, an antismear cylinder, or one or more skeleton wheels.
During the transfer of the printed sheets from one stage of the printing press to the next, the face of the freshly printed sheet which bears the fresh ink may be subject to contact with a portion of the transfer mechanism. The need arises to reduce the area of the transfer mechanism which contacts this freshly inked face.
lf the transfer mechanism is a form of transfer drum or cylinder, many different means have been incorporated into such a transfer mechanism to reduce the area of contact. Transfer drums have been designed with uneven surfaces, or with loose fabric material covering the surface of the drum, or with granular material spread sparsely over the drum in a particular pattern.
Skeleton wheels are normally thin wheels secured on a shaft adjacent one stage in a printing press in a manner that the thin circumferential surface of the wheel may contact only a chosen, reduced area on the freshly printed side of a sheet to perform its function of guiding the sheet to the next stage of the operation. Skeleton wheels may be slidable along the shaft upon which they are mounted so that the printer may select positions for the wheels which will provide the least area of contact of the wheels with printed matter, thereby reducing the likelihood of smearing.
I have found prior art which exeaplifies the concepts I have described above.
This prior art includes the following material:
______________________________________ U.S. Pat. No. 1,731,467 Knowlton Oct. 15, 1929 U.S. Pat. No. 2,085,845 Binkley July 6, 1937 U.S. Pat. No. 2,152,263 Knowlton March 28, 1939 U.S. Pat. No. 2,555,319 Cross June 5, 1951 U.S. Pat. No. 2,740,355 Wimpfheimer April 3, 1956 U.S. Pat. No. 3,261,288 Dickerson July 19, 1966 U.S. Pat. No. 3,308,522 Miller March 14, 1967 U.S. Pat. No. 4,402,267 DeMoore Sept. 6, 1983 German 261,143 Maschinenfabrik June 18, 1913 Augs. European Application 36,937 to Thoms Feb. 17, 1981 ______________________________________